*BSD News Article 54669


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From: tom@uniserve.com (Tom Samplonius)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: INND1.4+MMAP=BROKEN MESS
Date: 7 Nov 1995 00:18:34 GMT
Organization: UNIServe Online
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References: <46ldvj$l3c@buffnet2.buffnet.net> <imzqekgzmt.fsf@hidden.cs.uidaho.edu> <472u66$dpo@blackbush.xlink.net> <47f3gf$2gu@atlas.uniserve.com> <47m335$eu3@buffnet2.buffnet.net>
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In article <47m335$eu3@buffnet2.buffnet.net>, root@buffnet.net says...
>
>Tom Samplonius (tom@uniserve.com) wrote:
>: In article <472u66$dpo@blackbush.xlink.net>, hwr@xlink.net says...
>: >|> for about a week (was running on 2.0).  I am using MMAP, and it's
>: >|> working fine (I don't have the renumber problem).  I have two 
incoming
>: >|> feeds and over 6k active newsgroups.
>: >
>: >And I have 20 incoming feeds, > 60 outgoing and do have problems .. I 
>: >think that many problems just don't appear beaause machines are not 
loaded.
>
>:   I've seen this problem with mmap and INN too.  Basically, the active 
file wasn't 
>: staying current, and the hi index value was dropping behind, causing 
"cant symlink" 
>: errors.
>
>:   I believe the problem is related to swapping.  On heavy swapping 
systems, it will 
>: happen a lot.  It appears that when the mmap'ed active is paged out, 
sometimes it isn't 
>: written back to the file, but when it is paged in, it is read back from 
the file.

  A bug was found a couple of days ago, in the msync code.  It is quite 
likely the cause of the failed active file updates that happen with mmap 
under innd.  A partial fix is in -current.

  For now, just run innd without mmap.  On a FreeBSD system there is almost 
no performance difference between read/write and mmap anyway (due to unified 
disk cache and VM system).

Tom